* {
    margin: 0;
    padding: 0;
}

html {
    height: 100%;
}

/* 大背景 */
body {
    height: 100vh;
    background: url(../images/f1_1.jpg) no-repeat center 0 / cover;
    /* background-size: cover; */
}

/* 云 */
.cloud img {
    position: absolute;
    left: 50%;
}

.cloud img:nth-child(1) {
    margin-left: -250px;
    top: 20px;
    /* 
        linear：匀速 
        steps：分布动画，在工作中，配合精灵图实现精灵动画
        重复播放 3：重复3次，infinite：无限循环
        forwards 动画停止时在结束位置，backwards 停止时在开始位置（默认）
    */
    animation: icloud 1s infinite alternate linear;
}

.cloud img:nth-child(2) {
    margin-left: 400px;
    top: 100px;
    animation: icloud 1s infinite alternate linear 0.4s;
}

.cloud img:nth-child(3) {
    margin-left: -550px;
    margin-top: 200px;
    animation: icloud 1s infinite alternate linear 0.6s;
}

.text {
    position: absolute;
    left: 50%;
    top: 50%;
    /* 空间平移 */
    transform: translate(-50%, -50%);
    animation: text 1s;
}

@keyframes icloud {
    100% {
        transform: translate(20px);
    }
}

/* 默认 - 小 - 大- 小 - 默认 */
@keyframes text {
    0% {
        /* 
            transform: scale(0.5); 缩小
        */
        transform: translate(-50%, -50%) scale(1);
    }

    20% {
        transform: translate(-50%, -50%) scale(0.1);

    }

    40% {
        transform: translate(-50%, -50%) scale(1.4);

    }

    70% {
        transform: translate(-50%, -50%) scale(0.7);

    }

    100% {
        transform: translate(-50%, -50%) scale(1);
    }
}
